Africa Environment Outlook

WATER QUALITY IN CENTRAL AFRICA

The Kouiloo River, Congo-one of many rivers in the coastal area of Central Africa facing contamination by industry and siltation from excessive soil erosion.

Michel Gunther/Still Pictures

Freshwater quality in parts of central Africa is declining, as a result of: pollution from industrial and sewage outflows; agricultural run-off; and saltwater intrusion. The Congo River has been recognized as one of the cleanest in the world, due to the absence of industry, large urban settlements and agriculture along its banks (Johnson 1999). However, coastal areas are experiencing run-off and effluent from neighbouring agro-plantations and industries, which contaminate rivers, marshes and groundwater reserves. Clear felling in the hinterland also contributes to high rates of soil erosion, and to the siltation of rivers and estuaries. In particular, the Lobe and Kienke rivers (Cameroon) are especially high in sediment, which is deposited in the coastal zone and prevents the development of reefbuilding coral (World Bank 2000). Salinization occurs where freshwater sources come into contact with brackish or saltwater. The coastal industrial town of Douala in Cameroon has problems with the salinization of drinking water from aquifer resources, because rising sea levels facilitate permeation of underground aquifers by seawater. There is also inadequate provision of sanitation for the city's 1.4 million inhabitants, and raised nutrient levels are recorded in the estuary, as result of sewage discharge (Gabche and Smith 2001). Coastal freshwater resources are further threatened by sea level rise, which the IPCC predicts could be as much as one metre by 2100 (IPCC 2001).

The impacts of declining water quality are both ecological and social, with the contamination of freshwater habitat resulting in: losses of biodiversity; regulation of water flow; and reduced availability of exploitatable water for domestic, industrial, agricultural and recreational functions. There are also heightened risks of waterborne diseases associated with lack of potable water and sanitation, and costs of water treatment are increasing at a time when investment in this sector is already inadequate. For example, the drinking water supply in Yaounde, Cameroon, experiences occasional shortages and interruptions, driving many people to fetch water from alternative sources, such as springs and wells. A recent study of the bacteriological status of fifteen of these wells and springs revealed high densities of faecal bacteria and, thus, high risk of disease (Nola, Njine, Monkiedje, Sikati, Foko, Djuikom and Tailliez 1998). Several wetlands in the region have been degraded, due to the construction of dams and irrigation schemes, which divert water, and thus alter hydrological regimes. The reduction in water flow, and the increased silt and nutrient levels from agricultural return flows, have resulted in loss of favourable habitat and breeding grounds, and several wetland species have been lost.

Improving water quality in Central Africa

In response to pressures affecting water quality, many programmes and actions are under way in central Africa. These include: schemes for the drainage, purification and decontamination of freshwater systems; water management programmes; public awareness campaigns; ratification of relevant regional and transfrontier conventions for water resources protection and management; and efforts to implement water quality standards and control. National and international organizations have been instrumental in water supply and sanitation projects at the local level, and vehicles for international cooperation have been established for management of shared water resources. The Gulf of Guinea Large Ecosystem Project, for example, includes the management of land-based activities which contribute to declining water quality. The GEF-funded Reversal of Land and Water Degradation project has been initiated through the WB, in order to improve the management of resources in the Lake Chad basin. Gabon now has three Ramsar sites, following ratification of the Ramsar Convention in 1987 (Ramsar 2001), and Cameroon is undertaking the rehabilitation of wetlands that were compromised due to inappropriate development policies (see Box 2e.10).

Box 2e.10 Wetland rehabilitation in Cameroon

Each year, the Logone River (Cameroon) floods an area of about 6 000 km². This wetland supports large herds of giraffe, elephant, lions and various ungulates (including topi, antelope, reedbuck, gazelle and kob). Part of the floodplain has been designated as the Waza National Park, which attracts thousands of tourists per year, and which serves as a fish nursery in the flood season. Livestock grazing is also an important activity, supporting the livelihoods of many local communities. However, the wetland has been significantly reduced in size since the construction of a barrage across the floodplain in 1979.

This barrage created Lake Maga, which supplies water for the irrigation of nearby farmland. Fish stocks fell by 90 per cent, and grazing potential has decreased, impacting on local livelihoods. Plans to rehabilitate the wetland were established in 1993, and the embankments along the river were modified at an estimated cost of US$5 million over eight years. Stakeholders and local community members were involved in the planning and design of the project, which reinundated several thousand hectares of land. Small-scale fishing activities have recommenced, and clean water has been supplied to 33 villages from 37 wells. Together with training in health and sanitation, this has succeeded in lowering the incidence of diarrhoea by 70 per cent.

Source: Acreman 1999, IUCN 2001

Between 1990 and 2000, the percentage of the population with access to potable water supply increased from 52 per cent to 62 per cent in Cameroon, and from 59 per cent to 60 per cent in Central African Republic (WHO/UNICEF 2000). Access to sanitation has shown very slight increases, and rates are still far below other countries in Africa. Continued increased investment in this area is required, in order to mitigate pollution and the outbreak of diseases arising from inadequate sanitation and wastewater treatment.